pgriff44 Griffiths

Hi, left my employer end of May. Through a massive mistake on their part they continued to pay me for two months. I informed them of the mistake after two payments. They then issued a P45 which included the overpayment. They have now asked for the money back which of course I am willing to do. How do I correct this problem as regards to tax? Will they have to reissue the P45? I will not be working again this tax year. Hopefully you have all the information you need to help me.